Signal columns of this type are known from document FR 2 128 998. The supply conductors described in this document consist of blades comprising a first male connection end and a second female connection end. Homologous conductors situated in stacked stages are placed in series by introducing the male end of one into the female end of the other. The manufacture of such conductors entirely assuming the interconnection function is complicated. Furthermore, in these old columns each stage is supplied electrically by means of two specific conductors, this considerably multiplying the number of conductors at the base of the column.
Document EP 755 494 discloses a signal column in which the supply conductors are folded to form a U-shaped bridge at one end and an elbow at their other end. In this way homologous conductors situated in stacked stages are placed in series by elastic application of the elbow of the one with the U-shaped bridge of the homologous conductor of the other. However, this arrangement may result in contact faults because the connection quality is entirely assumed by the shape and elasticity of the conductors. Furthermore, as in the preceding document, each stage of the column is supplied by two conductors, yet the number of these conductors must be limited.
In order to limit the number of conductors, there is provided in each stage of the column a common conductor which, by connecting from stage to stage, extends from the lowermost stage to the uppermost stage, and, for each stage, an allocated conductor which originates from the lowermost stage and which does not have to be continued toward the immediately upper stage. The stage-to-stage connection is to this end brought about by means of an angular offset of the connecting points for the conductors, as is described in document FR 2 517 021. The disadvantage is that, if it is desired to give the various stages the same angular assembly position, use must be made of common conductors whose shape differs from that of the allocated conductors.
Document DE 100 41 202 describes a signal column having a number of stackable signaling elements. Each element is provided with a light source supplied from electrical conductors extending along its side wall. One conductor is common to all the signaling elements and supplies each of them. Another conductor is specific to the supply of each stage. Each conductor has a first end forming a junction bridge for an adjacent signaling element. The common conductor has the specific feature that it extends vertically along the column, whereas the conductors specific to each signaling element are offset angularly from one stage to the other. The junction bridge of the common conductor takes the form of a knot so that it can extend along this vertical axis. As in document FR 2 517 021, this document proposes using a conductor common to all the stages and specific conductors allocated to each of the stages. The proposed solution therefore makes it possible to limit the number of conductors. However, this solution requires the use of specific conductors whose shape differs from that of the specific conductors, this complicating the manufacturing method and increasing its cost.